1. Field of the Invention
This invention relates to a recording apparatus capable of exchanging the recording medium and, more particularly, to a device for memorizing the occurrence of an exchange of the recording medium.
2. Description of the Related Art
Recently, increasing numbers of portable instruments (for example, electronic still) have employed a recording apparatus using the rotary type of recording medium such as a magnetic disc or drum to record information (for example, a video signal) in successive concentric or annular tracks. Such an apparatus for convenient recording necessitates that provision for preventing double recording. In other words, prior to making a record, the recording head must be positioned in registry with a fresh track just next to the last recorded one.
A method for preventing double recording to be used in this kind of positioning mechanism is based on a process comprising the steps of detecting whether or not there is a recording on the given track to which the recording head is applied; as the recording medium is loaded; if so, then the recording head is moved to the next track and such a procedure is repeated until a first fresh track is reached, as, for example, disclosed in Japanese Laid-Open Patent Application No. Sho 54-140515 (corresponding to U.S. Pat. application Ser. No. 030,930 filed Apr. 17, 1979).
If such a method is used in combination with, for example, a control sequence that either when in completing the recording of one track, or when the next cycle of recording operation, the recording head is moved to the next track, the recording apparatus employing the same has an a ility to memorize where the first fresh track or the last recorded track lies respectively, since the relative position to the recording medium which the recording head is presently taking serves as an index therefor. In other words, even when the electrical power supply has once been cut off, or, in the case of the battery driving, when the battery as the electrical power source has been removed for replacement by a new one, or for recharging, or when the actual voltage of the battery has fallen below the threshold level, if the electrical power source is later thrown again, or recovers, the index is useful to that recording medium which was used in the preceding cycle of recording operation, provided the recording head is left unchanged in position therebetween. Hence, a new recording operation may be carried out from the position the recording head now has. This will not result in double recording or creation of a useless recording area (blank track).
With this feature alone, however, in the case when the recording medium has been exchanged at the time of cutoff of the electrical power supply in one way or another, the present position of the recording head loses its meaning. If the recording proceeds without re-adjustment of the position of the recording head, double recording or formation of a blank track will occur.
To cope with such a situation, the performance of the above-described process for positioning the recording head in registry with the track intended to be recorded has to be recycled each time the electrical power source is switched on. But, this is unreasonable insofar as there is no event of exchange of the recording medium. In application to the camera wherein the electrical power source is switched on in response to actuation of a camera release, the real-time recording capability (in the terminology of the ordinary camera, the so-called "snap" shooting) will be damaged in photographic situations. Further in the case of the battery driven instruments, premature consumption of electrical energy will result.
Even in application to types of apparatus other than that described above, for example, operating with selection of recording heads depending on the characteristic or sort of the recording medium used, or with means for setting various conditions for recording, a similar problem to that described above will arise.
To eliminate such a problem, the present patent applicant has made a previous proposal for providing a mechanism for memorizing the occurrence of an event of exchange of the recording medium and brought forth a method for re-adjusting the position of the recording medium in accordance with the operative position of the memory mechanism in Japanese Patent Application No. Sho 60-22633 corresponding to U.S. Pat. application Ser. No. 826.117 filed Feb. 5, 1986.
The memory mechanism proposed in the above-cited document has, however, because of its employing the mechanical memory, a drawback of increasing the number of parts of the apparatus. This is disadvantageous as respects manufacturability and cost. Moreover, an additional mechanism for erasing the mechanical memory becomes necessary and it takes a long time to complete the erasing operation. Thus, there is substantial room for improvement.